Rupert Murdoch’s 21st Century Fox has extended its guarantee over Sky News as part of its bid to buy parent company Sky.

The Murdoch-owned group tabled a series of measures to “guarantee” the editorial independence of Sky News earlier this month.

It followed concerns from Britain’s competition watchdog that a tie-up would hand the tycoon too much control over UK media.

Now, in an update to the Competition and Markets Authority (CMA), Fox extended the duration of the commitment to maintain a Sky-branded news service from at least five years to at least 10.

Rupert Murdoch (Ian West/PA)

And the Sky News board would be required, on an annual basis, to prepare a statement confirming that no instances of influence or attempted influence on the editorial output of Sky News have been escalated to it by the head of Sky News.

Fox is attempting to push through an £11.7 billion takeover bid for Sky.

The CMA previously said that Fox’s deal to buy the 61% of Sky it does not already own was “not in the public interest”.

Fox said its so-called “firewall remedies” would provide a commitment that “no employee or officer of 21st Century Fox, or a member of the 21st Century Fox board who is a trustee or beneficiary of the Murdoch Family Trust, will influence or attempt to influence the editorial choices made by the head of Sky News”.

An ongoing tussle over the deal has the potential to complicate Walt Disney’s 66 billion US dollar (£47 billion) takeover of 21st Century Fox’s entertainment assets, including Sky.

The competition watchdog has until May 1 before sending its final report on the bid to Culture Secretary Matt Hancock, who will then have 30 working days to make a final decision.